DISCRIMINATING against people based on nationality, religion or heritage is a very ignorant and potentially dangerous thing to do.

We only need to look at recent history to see that.

That is why I was stunned to see a news report about a Cairns business that has a sign saying it will not serve Israeli citizens posted on its wall.

In Australia, it is illegal to discriminate based on race, colour, sex, religion national extraction or social origin.

The owner of this business told the Cairns Post he put up the sign refusing to serve Israeli citizens because he doesn't agree with the policies of the Israeli government.

I wonder about this apparent blanket ban.

If a Palestinian with Israeli citizenship walked into this man's store, would he refuse to serve them?

After all, it is presumably in aid of their cause that he has started this boycott.

To me it's utterly bizarre - if I was in another country and they refused to serve me because they didn't like the policies of the Turnbull government, I would laugh in their face.

But for Jewish people, this refusal of service ties into one of the darkest periods of history when the Nazi Party organised a boycott of Jewish businesses and professionals and passed laws preventing Jewish people from being employed by Germany's civil service.

There were other anti-Jewish decrees as well, with Jews banned from military service in Germany, having their right to vote taken away, being banned from restaurants, parks and swimming pools and having passports restricted.

Some may accuse me of being oversensitive, but given that these discriminatory practices were followed by the decision to round up Jewish people and place them in ghettoes, and then by the Holocaust during the Second World War, one can see why the subject is of significance when it comes to discriminating against Israeli citizens, 78% of whom are Jewish.

Whether it's talking about banning Israelis, or Syrian people, or people with any background, one can see that it can be a slippery slope when one starts seeing someone as merely a nationality, or a religion, and not a person.

I sincerely hope this business owner rectifies his error and takes that sign down.